EMTB

OK. SO I tried this :

Edit functions.php
If you have access to the site via FTP, then this method will help you quickly get a site back up and running, if you changed those values incorrectly.

1. FTP to the site, and get a copy of the active theme’s functions.php file. You’re going to edit it in a simple text editor (like notepad) and upload it back to the site.

2. Add these two lines to the file, immediately after the initial “<?php” line.

update_option(‘siteurl’,’http://example.com/blog&#8217;);
update_option(‘home’,’http://example.com/blog&#8217;);
Use your own URL instead of example.com, obviously.

3. Upload the file back to your site, in the same location. FileZilla offers a handy “edit file” function to do all of the above rapidly; if you can use that, do so.

4. Load the login or admin page a couple of times. The site should come back up.

5. Repeat the above steps, but remove those lines. IMPORTANT: Do NOT leave those lines in there. Remove them immediately after the site is up and running again.

There are three other ways of doing this and you can find them here:http://codex.wordpress.org/Changing_The_Site_URL

Not sure that your problem is exactly like mine though.